1. Field of the Invention
The invention relates to an electric drive for a vehicle having a torque-transmitting device for transmitting torque from an electric motor to a vehicle wheel.
2. Description of the Prior Art
Electric drives are known, per se, for use especially in electric or hybrid vehicles and are supplied with electrical energy by a battery (actually an accumulator) or a fuel cell. In city driving, a hybrid vehicle uses the electric drive, for instance, producing no exhaust gas, while on the highway it uses an internal combustion engine that simultaneously recharges the battery.
The known electric drives, for instance in accordance with French Patent Disclosure FR 2 663 591 A, have an electric motor and a torque-transmitting device, for instance a gear, with which a torque of the electric motor can be transmitted to one or more vehicle wheels. An electric motor can be provided for driving all the vehicle wheels, the wheels of one axle, or one vehicle wheel.
It is also known to use the electric drive for braking the vehicle, by operating the electric motor as a generator and feeding electric current into the battery. However, this type of braking has the disadvantage that the braking torque is rpm-dependent, and thus the braking action is only slight at low speeds. Furthermore, the vehicle cannot be braked to a stop, since when it is stopped there is no braking action. Additional brakes, such as conventional disk or drum brakes, are therefore always necessary.